1. Field of the Invention
The present invention relates to medical devices. More particularly, the invention relates to occluding devices for occluding fluid flow through a body vessel.
2. Background of the Invention
Embolization coils have been used to stop undesired blood flow, such as for example, in the treatment of aneurysms, arteriovenous malformations, traumatic fistulae and tumor embolization. These conditions require that the blood flow through a portion of a body vessel be stopped, for example by introducing an artificial device into the vessel to slow the flow, and by letting the natural clotting process form a more complete blockage of the blood vessel with a clot.
Embolization coils can be used to form a blockage in a vein or artery to treat conditions like those listed in the foregoing paragraph. These devices have become increasingly common in procedures to block the flow of blood by promoting formation of a clot in a desired location. Embolization coils may be made from a bio-compatible material, such as platinum, to minimize the problems associated with tissue irritation and rejection. These coils typically have a pre-coiled tension that correspondingly shapes the coil upon deployment as a complex three dimensional curvy structure that fill in portions of the body vessel and slow blood flow therein. Often, polymeric fibers are added to the metallic coils to enhance the coil's thrombogenicity, which is the coil's ability to promote formation of clots.
Embolization coils are typically introduced into a body vessel by using a microcatheter which extends from a proximal point outside of the patient's body to a distal point near the embolization site. A loading device, e.g., a metal introducer sheath or cannula, containing the embolization coil is used to carry and protect the coil prior to transferring the embolization coil to the microcatheter for introduction into the patient. Typically, the loading device may have a small metal stopper or wire stopper that is used to hold the embolization coil within the loading device during packaging and shipping. When the interventionalist is ready to transfer the embolization coil to the microcatheter, she removes the stopper to release the coil into the microcatheter. Sometimes, however, the embolization coil falls out of the loading device prior to being transferred to the microcatheter. If the interventionalist is unaware that the loading device is empty, the occluding procedure may be temporarily performed on the patient without using the embolization coil until the interventionalist realizes the mishap. This will prolong the procedure and possibly present an unnecessary risk to the patient. Accordingly, further improvements and enhances to a device for transferring an embolization coil to a microcatheter for introduction into a patient are desirable.